package org.jeecg.modules.quartz.util;

import org.bouncycastle.crypto.AsymmetricCipherKeyPair;
import org.bouncycastle.crypto.params.ECPrivateKeyParameters;
import org.bouncycastle.crypto.params.ECPublicKeyParameters;
import org.bouncycastle.math.ec.ECPoint;

import java.io.IOException;
import java.math.BigInteger;

public class SM2Utils {
    //生成随机秘钥对
    public static SM2KeyPair generateKeyPair(){
        SM2 sm2 = SM2.Instance();
        AsymmetricCipherKeyPair key = sm2.ecc_key_pair_generator.generateKeyPair();
        ECPrivateKeyParameters ecpriv = (ECPrivateKeyParameters) key.getPrivate();
        ECPublicKeyParameters ecpub = (ECPublicKeyParameters) key.getPublic();
        BigInteger privateKey = ecpriv.getD();
        ECPoint publicKey = ecpub.getQ();
        return  new SM2KeyPair(Util.byteToHex(publicKey.getEncoded(false)),Util.byteToHex(privateKey.toByteArray()));
    }

    //数据加密
    public static String encrypt(byte[] publicKey, byte[] data) throws IOException {
        if (publicKey == null || publicKey.length == 0) {
            return null;
        }

        if (data == null || data.length == 0) {
            return null;
        }

        byte[] source = new byte[data.length];
        System.arraycopy(data, 0, source, 0, data.length);

        Cipher cipher = new Cipher();
        SM2 sm2 = SM2.Instance();
        ECPoint userKey = sm2.ecc_curve.decodePoint(publicKey);

        ECPoint c1 = cipher.Init_enc(sm2, userKey);
        cipher.Encrypt(source);
        byte[] c3 = new byte[32];
        cipher.Dofinal(c3);
        //C1 C2 C3拼装成加密字串
        return Util.byteToHex(c1.getEncoded(false)) + Util.byteToHex(source) + Util.byteToHex(c3);
    }

    //数据解密
    public static byte[] decrypt(byte[] privateKey, byte[] encryptedData) throws IOException {
        if (privateKey == null || privateKey.length == 0) {
            return null;
        }

        if (encryptedData == null || encryptedData.length == 0) {
            return null;
        }
        //加密字节数组转换为十六进制的字符串 长度变为encryptedData.length * 2
        String data = Util.byteToHex(encryptedData);
        /** 分解加密字串
         * （C1 = C1标志位2位 + C1实体部分128位 = 130）
         * （C3 = C3实体部分64位  = 64）
         * （C2 = encryptedData.length * 2 - C1长度  - C2长度）
         */
        byte[] c1Bytes = Util.hexToByte(data.substring(0,130));
        int c2Len = encryptedData.length - 97;
        byte[] c2 = Util.hexToByte(data.substring(130,130 + 2 * c2Len));
        byte[] c3 = Util.hexToByte(data.substring(130 + 2 * c2Len,194 + 2 * c2Len));

        SM2 sm2 = SM2.Instance();
        BigInteger userD = new BigInteger(1, privateKey);

        //通过C1实体字节来生成ECPoint
        ECPoint c1 = sm2.ecc_curve.decodePoint(c1Bytes);
        Cipher cipher = new Cipher();
        cipher.Init_dec(userD, c1);
        cipher.Decrypt(c2);
        cipher.Dofinal(c3);

        //返回解密结果
        return c2;
    }

    public static void main(String[] args) throws IOException {
        // 获取公钥私钥对
        SM2KeyPair sm2KeyPair = SM2Utils.generateKeyPair();

        // 获取公钥和私钥
        String publickey=sm2KeyPair.getPublicKey();
        System.out.println("publickey："+publickey);
        String privatekey=sm2KeyPair.getPrivateKey();
        System.out.println("privatekey："+privatekey);

        // 需要加密的信息
        String info="哈哈哈，嘿嘿嘿";
        // 将信息加密，公钥的字节码需要使用util里的hexToByte方法
        String encrypt = SM2Utils.encrypt(Util.hexToByte(publickey), info.getBytes("utf-8"));

        System.out.println("加密后信息："+encrypt);

        // 将加密后的信息解密，私钥和加密后的数据的字节码对象需要用util里的hexToByte方法
        byte[] decrypt = SM2Utils.decrypt(Util.hexToByte(privatekey), Util.hexToByte(encrypt));
        // 将字节数组转为字符串
        String newInfo=new String(decrypt,"utf-8");
        System.out.println("解密后信息:"+newInfo);
    }
}
